The major objective of the proposed investigations is to introduce new and perhaps better opisthobranch models for biomedical research. Development of research models implies that the particular organisms be made readily available and that they are unusually suitable for one or more particular types of research. Because opisthobranches (e.g., Aplysia and Tritonia) possess large, identifiable nerve cell bodies and exhibit a diversity of behaviors, they have been utilized in a broad range of behavioral and neurobiological investigations. However, current limitations to progress in these areas include: (1) periodic unavailability of animals due to seasonality, and (2) inability to study age-dependent phenomena (e.g., development and aging). Laboratory culture of animals through their entire life cycle would remove these limitations to continued rapid progress and provide expanded opportunities for new research (e.g., behavioral genetics). Focus of these investigations will be: (1) on developing simple, reliable laboratory mariculture techniques for six opisthobranch species (three aplysiids and three nudibranchs); (2) on defining life historical, behavioral, anatomical, and physiological characteristics which make the selected models useful in biomedical research; and (3) on manipulation of environmental parameters of food, light, temperature, and density to define conditions which produce optimal growth, size and generation time for each species. Success with the proposed research will simultaneously supply additional opisthobranch models for comparative studies, and provide laboratory rearing techniques which may be used by other investigators for producing unlimited stocks of animals of known age and background.